Abiracho struck by earthquake with seismic intensity of upper 6

The earthquake with maximum intensity 7 on the Japanese scale that struck Hokkaido Sept 6, 2018, was named "Hokkaido Eastern Iburi Earthquake" as it was centered in the mid-eastern part of the Iburi region. The Iburi region is located on the south side of central Hokkaido and has Muroran City in the west, Tomakomai City in the center and Atsumacho, Abiracho and Mukawacho in the east.

The earthquake registered an upper 6 to 7 on the Japanese seismic scale of 7 and caused serious damage as many houses collapsed in the earthquake's epicenter such as in Atsumacho, Abiracho and Mukawacho. In Atsumacho, a large landslide occurred, damaging the Tomatoh Atsuma Thermal Power Plant and triggering a large-scale power outage with two out of the three power generators stopping.

At Hayakita Shrine in Hayakitaomachi District, Abiracho, all four stone lanterns fell while part of the front shrine collapsed with its roof falling down, showing how powerful the earthquake was (Fig. 1 & 2).

Fig. 1: Part of front shrine collapsed at Hayakita Shrine in Abiracho (source: Nikkei BP)

Fig. 2: Fallen stone lantern at Hayakita Shrine following earthquake (source: Nikkei BP)

Over 100MW mega-solar plant directly hit

The "SoftBank Tomatoh Abira Solar Park," a mega- (large-scale) solar plant with an output of about 111MW, started operation in December 2015 in Abiracho, the earthquake's epicenter (Fig. 3).

Fig. 3: Panoramic view of "Softbank Tomatoh Abira Solar Park" (source: SB Energy)

The power producer is a special purpose company (SPC) jointly financed by SB Energy Corp, which is engaged in renewable energy business in the SoftBank Group, and Mitsui & Co Ltd. The power plant was constructed on about 1,660,000m2 of land owned by Tomatoh Inc (Tomakomai City, Hokkaido), which leads land development in the eastern Tomakomai area. The SPC rented the land from Tomatoh and raised funds by structuring project finance.

Toshiba Corp provided engineering, procurement and construction (EPC) services, adopting its own solar panels and PV inverters of Toshiba Mitsubishi-Electric Industrial Systems Corp (TMEIC). Toshiba also provides operation and maintenance (O&M) services while Nihon Techno Co Ltd (Shinjuku-ku, Tokyo) offers security and management services at the plant.

Immediately after the earthquake, the Tomatoh Abira Solar Park stopped operation upon detecting the connected grid's power outage and disconnected from the grid. Although having been struck by a major quake with a seismic intensity of upper 6, there was no damage to the extra-high-voltage transformer facilities and substation equipment. However, some foundations and mounting systems were found to have tilted slightly (Fig. 4).

Fig. 4: Some arrays tilted due to earthquake (source: Nikkei BP)